Midori Hayakawa comes from a wealthy family. Upon joining the Fujimi Academy volleyball team, her initial selfishness and belief in her own superiority lead her to covet the captaincy, sparking conflicts with protagonist Kozue Ayuhara as she tries to undermine Kozue.

Repeated confrontations and eventual reconciliation with Kozue drive Midori's significant character development, transforming her from rival into Kozue's closest friend and staunchest ally. She solidifies her position as the team's second-best player, frequently coordinating specialized attacks with Kozue and serving as the series' deuteragonist.

Midori confronts substantial personal challenges, including intense competitive pressure, injuries, and emotional struggles. Despite lacking elite volleyball height, she compensates through rigorous training and fierce determination, making resilience her defining trait as she persists through setbacks in pursuit of volleyball excellence.

Romantic subplots involve ship tease with soccer player Mitamura, suggesting mutual interest, though these elements remain secondary to her athletic journey, adding depth without overshadowing her primary role.

The 2005 live-action drama adaptation presents distinct elements: Midori initially surpasses Kozue in skill, fueling greater resentment when Kozue earns national team selection over her. This jealousy intensifies due to Midori's longstanding romantic feelings for Tsutomu Ichinose, who prefers Kozue. Midori's omission of Kozue's removal from the national team – and her own subsequent selection as replacement – further strains their relationship. These conflicts eventually resolve, allowing both to represent Japan together.

Across all media, Midori evolves from an antagonistic figure into a symbol of perseverance and loyalty. Her journey emphasizes teamwork, emotional growth, and the complexities of friendship within competitive sports.